<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        html{
            height: 100%;
        }
        body{
            background-color: rgb(194, 226, 255);
            height: 100%;
        }
        .d1{
            width: 1000px;
            height: 100%;
            background-color: #d4ff29;
            text-align: center;
            /* 居中 */
            margin: auto;
        }
    </style>
</head>
<body>
    <div class="d1">
        在浏览器视窗中居中
    </div>
</body>
</html>